Vented spray gun cup



March 15, 1966 1-. w. DALTON, JR

VENTED SPRAY GUN CUP INVENTOR.

Filed March 9, 1964 l lo/was WDQLTON, r12.

fir TOENEYS United States Patent 3,240,398 VENTED SPRAY GUN CUP Thomas W. Dalton, Jr., Playa Del Rey, Califi, assignor to Sharpe Manufacturing Company, Los Angeles, Calif., a corporation of California Filed Mar. 9, 1964, Ser. No. 350,436 4 Claims. (Cl. 222-193) This invention relates to apparatus for spraying paint or other liquids, and particularly to a cup structure secured to the spray gun in which the paint or other liquid is contained. Flow of pressurized air through or about the gun nozzle, and in a well-understood manner, creates a partial vacuum at the discharge opening of the nozzle. Atmospheric pressure acting upon the contents of the cup, and communicated thereto through a suitable vent opening, accordingly urges the liquid contents of the cup to a delivery conduit and then to the discharge opening of the nozzle. The delivery conduit may be mounted by the cover for cup, with its inner end projecting to the bottom of the cup, and its outer end joined to the gun or provided with a fitting for detachable connection to the gun. The vent opening is usually formed in the cover near one edge thereof.

The existence of the vent opening has, in the past, generally confined the use of a spray gun by virtue of the danger of leakage of liquid through the vent opening. Thus, if the vent opening is located behind the delivery conduit, the user of the gun cannot tilt the gun rearwardly about a horizontal axis without danger of spilling liquid. As the level of liquid in the cup is reduced, the danger is lessened; yet it exists. For this reason, the user may prefer only partially to fill the cup, sacrificing the labor attendant upon more frequent refilling in favor of increased mobility of the cup.

The primary object of this invention is to provide a novel cup structure that allows the cup to be entirely filled without any danger of the liquid contents spilling out through the vent opening whatever may be the orientation of the cup.

Another object of this invention is to provide a structure of this character that requires no valves or other moving parts susceptible to malfunction in contact with paint or other liquid.

Still another object of this invention is to provide a structure of this character that is easily cleaned and maintained.

The foregoing objects are achieved by using a conduit for extending the vent so that the outer end of the vent opening is accessible to the liquid through a trapped column of air if the inner end of the conduit is below the liquid level. If the inner end of the conduit is above the liquid level, there will of course be no leakage. The conduit is so arranged that a column of air must be trapped before liquid can flow through the outer end of the vent opening. Accordingly, while spraying, the differential pressure causes the column of air to be extended to the inner end of the conduit, and liquid is prevented from entering by virtue of the difierential in pressure. Before spraying is stopped, the cup is righted or returned at least to a position in which either the inner or outer end of the conduit is above the liquid level.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose, there are shown a few forms in the drawings accompanying and forming part of the present specification, and which drawings, unless as otherwise indicated, are true scale. These forms will not be described in detail, illustrating the general principles of the invention; but it is to be understood that 3,249,398 Patented Mar. 15, 1966 'ice this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a side elevational view of a spray gun and cup incorporating the present invention, the cup being shown in axial sectional view;

FIG. 2 is an enlarged sectional view taken along a plane corresponding to line 22 of FIG. 1; and

FIG. 3 is a sectional view similar to FIG. 2, but illustrating a modified form of the present invention.

In FIG. 1 there is illustrated a spray gun 10 having a head 11 in which a nozzle structure (not shown) is removably secured, as by the aid of the spray gun tip 12. Air under pressure is caused to flow through or around the nozzle in order to induce flow of material upwardly through a depending conduit 13 attached to the head 11. Air under pressure is admitted through a hose 9 con-' nected at the grip portion 14 of the gun. Air passes about a control valve 15 and a throttle valve 16 to the head 11. The control valve 15 is operated by a trigger piece 17 pivoted on the gun.

A cup structure 18 forms a reservoir for supplying paint or other material to the gun conduit 13. The cup 18 has a lid cover 19 at which a discharge conduit 20 is mounted. The discharge conduit 20 extends from the bottom of the cup through and beyond an apertured boss 21 at the center of the lid 19. A fitting 22 secured to the medial portion of the discharge conduit 20 serves as a means for mounting the discharge conduit 20. The fitting 22 has an intermediate flange 23 seated at an outwardly facing shoulder or seat 24 formed in the aperture of the boss 21. The lower or inner end of the fitting 22 is threaded and projects beyond the boss. A lock nut 25 engages this threaded end and draws the flange 23 into sealing engagement with the shoulder or seat 24.

A bridge 26 pulls the lip 27 of the cup into engagement with a sealing gasket 28 mounted on the inside of the lid 19. The bridge 26 is generally of U-shaped configuration. A threaded apertured hub or boss 29 at the center of the bridge surrounds the discharge conduit 20. The legs of the bridge 26 are provided with hooked ends 30 and 31 for engaging beneath pins 32 and 33 projecting outwardly from the neck of the cup 18. The hooked ends 30 and 31 may be moved into position by angular movement of the bridge with the lid about the axis of the cup.

By moving the bridge 26 outwardly or upwardly of the lid 19, the hook ends 30 and 31 pull the pins 32 and 33 toward the lid 19 and thus a suitable seal is effected. For this purpose, a locking lever or spinner 34 is provided. The spinner 34 surrounds the discharge conduit 20 and has a tubular part provided with interior threads and exterior threads. The interior threads engage the threaded upwardly extending end of the mounting fitting 22 and the outer threads engage the interior threads of the bridge hub 29. The outer threads are substantially coarser than the interior threads. Accordingly, as the spinner 34 is rotated upon the threaded end of the fitting 22, the bridge is moved outwardly or inwardly depending upon the direction of rotation, and in accordance with the diiference in pitch of the threads.

The upper end of the discharge conduit 20 has threadedly attached thereto a stem 35. This stem 35 has a reduced extension threadedly received in the ,tube end. Between the shoulder 36 formed by the reduced extension and the end of the tube 20 is a stop washer 37. The upper end of the stem 35 has a conical or spherical convex surface that engages a conical or spherical seat formed at the lower end of the conduit 13. A swivel nut 38 secures the parts together.

In order to allow for the admission of ambient air to the cup 18, thus to discharge the liquid in the cup through the conduit 20, a vent opening 39 is provided in the lid 19 near the lid rim but inside the seal ring 28. A right angle or L fitting 40 is threadedly attached inside the lid 19 with the end of the fitting oriented substantially tangentially. On the inner end of the fitting there is attached a tube. 41 that extends arcuately about the axis of the lid and adjacent the inner surface thereof, as indicated in FIG. 2. The tube 41 is attached to the fitting 40 by the aid of a companion threaded fitting 42.

The tube 41, and the fittings 42 and 40 together constitute a vent conduit, with the inner open end 43 thereof situated substantially diametrically of the outer end opening 39.

In normal operation, no discharge of contents will result because either the inner or outer end of the vent conduit will be above the level of liquid in the container. Thus if the gun is tilted rearwardly, the inner end 43 remains above the level even though the container or cup 18 is substantially full. If the container is tilted forwardly the outer end remains above the liquid level and again no leakage will occur.

However, merely by maintaining a fiow of pressurized air past the nozzle during all times when the container or cup 18 is tilted, it is absolutely ensured that there will be no leakage. Thus the inner end 43 of the vent conduit is entirely submerged before any significant quantity of fluid can flow along the vent conduit. This means that a column of air will be trapped in the conduit, which is at atmospheric pressure; but the fluid pressure is less due to the flow of air past the gun nozzle. Hence the trapped air column keeps the liquid in the cup 18, and bubbles into the container. Leakage is thus prevented.

Before the trigger 17 is released, the cup 18 is righted. This locates the vent conduit above the liquid level, and leakage is prevented.

In FIG. 3, a vent conduit extending substantially 360 about the cup is provided. The vent conduit can have a variety of configurations.

Preferably the conduit should be extended and curved so that the inner and outer ends of the vent conduits are out of alignment and so that the path between the inner and outer ends of the vent conduit has an upwardly extending part whatever the orientation of the cup and the quantity of fluid in the cup.

The inventor claims:

1. In combination: a spray gun cup; a removable lid for sealing the cup, and having a vent opening in uninterrupted communication with the ambient space, a discharge conduit having an inner end located adjacent the bottom of the cup and an outer end cooperable with a spray gun for subjecting the discharge conduit to a partial vacuum for drawing material from the cup; and a conduit forming an extension of the vent opening on the inside of the lid and having an inner open end spaced from said vent opening, an intermediate portion of the conduit lying entirely beyond any straight line joining, the vent opening and said inner open end of said conduit.

2. In combination: a spray gun cup; a removable lid for sealing the cup, and having a vent opening in uninterrupted communication with the ambient space; a discharge conduit having an inner end located adjacent the bottom of the cup and an outer end cooperable with a spray gun for subjecting the discharge conduit to a partial vacuum for drawing material from the cup; and a conduit forming an extension of the vent opening on the inside of the lid and having an inner open end spaced from said vent opening with the axial projection of said inner opening along the conduit entirely out of alignment with the vent opening, an intermediate portion of the conduit lying entirely beyond any straight line joining the vent opening and said inner open end of said conduit, said conduit extending substantially in a plane parallel to the lid and adjacent the inside of the lid whereby the entire conduit is nonnally above the level of liquid in the cup.

3. In combination: a spray gun cup; a removable lid for sealing the cup, and having a vent opening in uninterrupted communication with the ambient space located adjacent the rim of the lid; a discharge conduit having an inner end located adjacent the bottom of the cup and an outer end cooperable with a spray gun for subjecting the discharge conduit to a partial vacuum for drawing material from the cup; and a conduit forming an extension of the vent opening on the inside of the lid and having an inner open end spaced from said vent opening, said conduit being non-rectilinear, extending arcuately about the center of the lid in a plane parallel to the lid and to a point located substantially diametrically opposite said vent opening whereby a column of air is trapped in said conduit when the cup and its liquid contents are tilted to a position in which said inner opening is at or below the level of said liquid contents.

4. In combination: a spray gun cup; a removable lid for sealing the cup, and having a vent opening in uninterrupted communication with the ambient space located adjacent the rim of the lid; a discharge conduit having an inner end located adjacent the bottom of the cup and an outer end cooperable with a spray gun for subjecting the discharge conduit to a partial vacuum for drawing material from the cup; and a conduit forming an extension of the vent opening on the inside of the lid and having an inner open end spaced from said vent opening, said conduit being non-rectilinear and extending circularly about the center of the lid for substantially 360 whereby a column of air is trapped in said conduit when the cup and its liquid contents are tilted to a position in which said inner opening is at or below the level of said liquid contents.

References Cited by the Examiner UNITED STATES PATENTS 1,207,274 12/1916 Carter 239371 X 1,911,367 5/1933 Kitto 239-371 X 2,303,458 12/1942 Hermann et al 222-193 2,608,446 8/1952 Pota 222193 X 3,157,360 11/1964 Heard 239-415 X FOREIGN PATENTS 508,734 7/1939 Great Britain.

LOUIS J. DEMBO, Primary Examiner, 

1. IN COMBINATION: A SPRAY GUN CUP; A REMOVABLE LID FOR SEALING THE CUP, AND HAVING A VENT OPENING IN UNINTERRUPTED COMMUNICATION WITH THE AMBIENT SPACE, A DISCHARGE CONDUIT HAVING AN INNER END LOCATED ADJACENT THE BOTTOM OF THE CUP AND AN OUTER END COOPERABLE WITH A SPRAY GUN FOR SUBJECTING THE DISCHARGE CONDUIT TO A PARTIAL VACUUM FOR DRAWING MATERIAL FROM THE CUP; AND A CONDUIT 